Effects of heterogeneous flow on carbon conversion in gas-solid circulating fluidized beds

Abstract

Gas-solid fluidized beds have heterogeneous flow structures, which affect the reactions due to uneven distribution and limited mixing of reactants. Some model approaches neglect these heterogeneous structures and use a homogeneous assumption instead. This work demonstrates the effects of neglecting this heterogeneity. Eulerian multiphase modeling is utilized to model fuel conversion in a fluidized bed riser. The effects of the chemical reactivity of the fuel, the amount of fuel in the reactor and the fluidization regime are investigated. The model data are time- and space-averaged into 1D results and compared with a 1D modelling which assumes homogeneous distributions in radial direction. Based on this study, the negligence of the heterogeneous flow structures leads to significantly higher local and overall reaction rates and conversion in the system.